Results of forest enrichment by planting native broadleaf tree species in the model forests of APFNET project in Tan Son district, Phu Tho province

Abstract

Natural forests at Thu Cuc commune, Tan Son district, Phu Tho province are classified as poor (in terms of wood volume) and have low biodiversity. Forest states are primarily Ia, Ib, IIa, IIb, IIIa1 and mixed forests of timber and bamboo species. Species composition is simple and is mainly Mallotus apelta, Macaranga denticulatus, Mallotus barbatus, Vernonia arborea,
Litsea cubeba. Natural regeneration is of poor quality and quantity and includes mainly light - demanding pioneer species. Based the forest states in the research area, the project aimed to establish pilot models of forest enrichment by planting native broadleaf tree species including Erythrophleum fordii, Michelia mediocris, Manglietia conifera, Dipterocarpus retusus, and Parashorea chinensis. Nineteen months after
planting, survival rates were above 75% and the proportion of surviving trees that are fast - growing and healthy is over 85% in all of pilot models. Most species in the models have grown well: Erythrophleum fordii, D00 = 1.14 - 1.19cm, Hvn = 0.96 - 1.1m, averaged across all models; Parashorea chinensis, D00 = 1.15 - 1.2cm, Hvn= 1.1 - 1.3m; Dipterocarpus retusus D00= 2.0 - 2.1cm, Hvn= 1.55 - 1.8m; Michelia mediocris D00 = 2.05
- 2.17cm, Hvn = 2.06 - 2.08m and Manglietia conifera D00= 1.26 - 1.37cm, Hvn = 1.6 - 1.65m. The highest figure of mean annual increment of D 00 belongs to Dipterocarpus retusus, at 1.08 - 1.2cm/year. In contrast, Erythrophleum fordii had the lowest growth at 0.34 - 0.39cm/year. Similarly, Manglietia conifera reached the highest of 0.65 m/year in height top, but Erythrophleum fordii is the lowest figure being 0.1 - 0.2m/year.